weak_map: replace entries in one lookup and research ephemron vs key/value pair for insert#50
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nekevss merged 3 commits intoboa-dev:mainfrom Mar 16, 2026
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shruti2522
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nekevss
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Mar 13, 2026
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| ### `WeakMap<K, V>` | ||
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| It's a `HashMap<usize, ArenaPointer<Ephemeron<K, V>>>`, |
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nit: early feedback, but let's try to keep the notes as a time capsule. Create a new note and link to this one as a revision
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Sure, will do that
…/value pair approach for insert
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Added a new note explaining the changes made here and conclusion on key/pair vs. ephemeron. Ready for review now |
nekevss
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Mar 16, 2026
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| fn insert_ptr( | ||
| // replace an existing entry in one lookup, invalidating the old ephemeron | ||
| fn replace_or_insert( |
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suggestion: let's make this insert, and return an Option.
This API is pretty standard for various other Rust map types, and we should adhere to it where possible.
…/value pair approach for insert
nekevss
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Mar 16, 2026
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Let's move forward with this! Thanks :)
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Replaced the two step remove+insert update path with a single
find_entrylookup + in place swap (mem::replace) in both mark_sweep and mark_sweep_arena2. Added functionreplace_or_insertto weak map internalskey/value pair vs. ephemeron:
I have looked into this thoroughly whether
WeakMap::insertshould take a prebuiltEphemeroninstead of (key,value), and here's what I have found.I think key/value pair is the better approach. Taking an
Ephemeronin insert would leak GC internals into the API, also it would make callers responsible to perform any collector specific allocation and queue registration which is wrong since the collector must own these to preserve invariants around sweeping and reclamationWIP: this includes changes from Hashmap -> HashTable too since the changes here needed it, will be ready for review once that PR lands